Store thousands of items in a new item, called Buffer!
Carry them around or place it down to act as a chest!
Use items and blocks from within it as if you were placing them normally!
Switch selected item.
Switch pickup mode.
Switch void mode.
Items will be picked up by the Buffer and placed inside it.
Items picked up / inserted will be voided if they exceed the Buffer's limit.
Use PgUp to select a block or item within the Buffer. While that is selected, the Buffer acts as that block or item during placement.
To activate the GUI, please select the Buffer with PgUp then right-click.